diff --git a/parser/ast/ddl.go b/parser/ast/ddl.go
index aecffc69..f9ea31d6 100755
--- a/parser/ast/ddl.go
+++ b/parser/ast/ddl.go
@@ -823,7 +823,7 @@ func (n *DropTableStmt) Restore(ctx *format.RestoreCtx) error {
 			ctx.WritePlain(", ")
 		}
 		if err := table.Restore(ctx); err != nil {
-			return errors.Annotate(err, "An error occurred while restore DropTableStmt.Tables "+string(index))
+			return errors.Annotatef(err, "An error occurred while restore DropTableStmt.Tables[%d]", index)
 		}
 	}
 
diff --git a/parser/lexer_test.go b/parser/lexer_test.go
index d313bb4c..74341836 100644
--- a/parser/lexer_test.go
+++ b/parser/lexer_test.go
@@ -198,7 +198,7 @@ func (s *testLexerSuite) TestscanString(c *C) {
 		{`' \n\tTest String'`, " \n\tTest String"},
 		{`'\x\B'`, "xB"},
 		{`'\0\'\"\b\n\r\t\\'`, "\000'\"\b\n\r\t\\"},
-		{`'\Z'`, string(26)},
+		{`'\Z'`, string(rune(26))},
 		{`'\%\_'`, `\%\_`},
 		{`'hello'`, "hello"},
 		{`'"hello"'`, `"hello"`},